In known imaging systems, during medical imaging examination there are angles at which X-ray exposure is not performed (or not performed using high intensity X-ray beams) and this lack of data may prevent 3D image reconstruction from 2D images or reduce quality of a 3D image reconstruction. In order to avoid this, multiple imaging passes are performed in order to try to cover spatial and angular gaps and obtain exposure from almost all angles within a desired range. Known systems perform these additional imaging passes while performing radiation exposures during a rest phase of a heart indicated by an ECG signal. Each additional imaging pass is timed to start at a different point within a cardiac cycle to fill imaging spatial and angular gaps. However, duration of sequential heart cycles is not known and variable and need to be estimated. This potential inaccuracy, together with inaccuracies due to other disturbances in a normal hearth rhythm, results in either exposure overlaps or leftover spatial gaps in coverage. This may result in a patient receiving surplus X-ray exposure during overlap imaging and reduced image quality from gaps in angular coverage. A system according to invention principles addresses these deficiencies and related problems.